Brighton streetscape standards 2018 (1).pdf

SECTION 4

All Streets The following standards apply to all street classifications city-wide, except where specific areas have applicable planning documents that set forth alternative standards tailored to the area.

4.1

STREET TREES

Rows of street trees along street edges are the fundamental, unifying element of continuity in city streetscapes.

Street trees can be considered as multi-functional public infrastructure that:

• Defines the street as distinct space, providing a unifying framework for abutting developments.

• Provides canopy shading along streets and sidewalks to reduce glare and summer heat build-up.

• Provides a buffer between pedestrians on the sidewalk and vehicles in the roadway.

• Provides space for streetlights and signs, and for snow storage in winter.

Street trees in an arterial parkway.

4.1.1 Tree planting in parkways.

Wherever the sidewalk is separated from the curb in accordance with the Larimer County Urban Area Street Standards, rows of canopy shade trees shall be planted in the parkway at 30 to 40 foot intervals, centered between the curb and the sidewalk.

Street trees in a local street parkway.

4.1.2 Species groupings within tree

rows.

To the extent reasonably feasible, street tree rows in landscape areas, whether inside or outside of the sidewalk, shall be in groupings of three, five, or more of a single species. The intent is to provide a degree of species diversity within a deliberate, repeating design pattern.

Designers are encouraged to arrange changes in species to reflect roadway conditions, such as open stretches of roadway between access points, stretches approaching intersections and driveways, and/or changes in adjoining land use.

Plan view illustration of street trees showing groupings.

4.1.3 Street trees in sidewalk

cutouts.

If a project involves a new sidewalk that must be attached to the curb due to unique constraints or context, then the sidewalk width shall be wide enough to incorporate planting cutouts with tree grates to the maximum extent feasible.

• To the maximum extent feasible, such sidewalks shall be 12-15 feet wide with cutouts at least 25 square feet at 30- to 50-foot spacing.

Larger cutouts with more than 25 square feet are encouraged.

• In all cases, trees in sidewalk cutouts shall be located at least 8 feet away from buildings and offset from building entrances.

• If such an attached sidewalk has an abutting landscape area, then 8 feet shall be the minimum width in which canopy trees shall be provided in sidewalk cutouts.

• The minimum area of any sidewalk cutouts shall be 16 square feet, using 4x4-foot tree grates. Larger cutouts with more than 16 square feet of area are encouraged, for example 4x6-foot or 4x9-foot tree grates, to support tree health.

8-foot sidewalk with 4’x4’ tree grates, where there is an abutting landscape area.

• The soil surface in a sidewalk cutout shall be level with the bottom of the sidewalk slab. Trees shall then be planted with the top of the root ball 1-2 inches above the soil surface.

• All tree grates shall be installed per manufacturer’s instructions.

Frames shall be set in a true, flat plane to prevent rocking of the grate. The grate or a template shall be set in the frame before concrete is poured to ensure the final installation is square and flat.

• Grates shall be of a pedestrian-safe

ADA-compliant style with slot openings 3/8-inch or less.

• A spacing interval up to 50 feet shall be permitted for street trees in grates where abutting commercial buildings face the street with no intervening vehicle use area between the street and the building.

4.1.4 Tree planting outside of

sidewalks where existing constraints preclude parkway tree planting or sidewalk cutouts.

Where a sidewalk is attached to the curb and is less than 8 feet in width, canopy shade trees shall, to the extent reasonably feasible, be established in an area ranging from 3 to 7 feet behind the sidewalk at 30 to 40 foot intervals.

This standard shall also apply where unusual constraints preclude tree planting in a parkway.

Any such planting will typically require coordination with abutting property owners.

Examples of street trees outside of sidewalks.

4.1.5 Adjustment of spacing

intervals.

The Director or the City Forester may approve or require larger or smaller spacing intervals to better fit the growth habits of different street tree species, for safe use of the street or sidewalk, and to better fit with existing trees or other existing conditions unique to the location.

4.1.6 Overhead power line conflicts.

Ornamental trees may be planted in substitution of the canopy shade trees where overhead lines and fixtures prevent normal growth and maturity.

4.1.7 Spacing from driveways.

No tree shall be planted closer than 8 feet from any driveway or alley.

4.1.8 Tree separation from utilities.

Landscape and utility plans shall be coordinated. Following are the minimum dimension requirements for the most common tree/utility separations.

• 40 feet between canopy shade trees and streetlights. Fifteen (15) feet between ornamental trees and streetlights.

• 10 feet between trees and water or sewer lines.

• 4 feet between trees and gas lines.

• 4 feet between trees and underground electric lines shall be provided to the extent reasonably feasible.

Exceptions to these requirements may occur where utilities are not located in their standard designated locations, as approved by the City Forester or the Director. Tree/utility separations shall not be used as a means of avoiding the planting of required street trees.

Tree separations from streetlights and driveways.

8’ min.

D r i v e w a y

40’ min.

Canopy Shade Trees

15’ min.

Ornamental

Trees

4.2

PARKWAY LANDSCAPING – TURF-

TYPE GRASS

Turf-type grass in parkways provides a multi-functional solution for landscaped edges along city streets of all classifications. Two main types of turf-type grasses may be used in streetscapes: cool-season turfgrasses, and warm-season native shortgrasses.

Cool-season turfgrasses include improved varieties of Kentucky Bluegrass, Tall Fescue, Perennial Ryegrass, and Wheatgrasses. Warm-season native shortgrasses include improved varieties of Buffalograss and Blue Grama.

Efficiently irrigated, mowed cool-season turfgrass provides a living green edge to city streets over a long growing season. The green edge, along with street trees, is a unifying element that helps define City streets as continuous spaces, in conjunction with street trees.

Cool-season turfgrass can be a sustainable, functional landscape solution consistent with “xeriscape” and “water-wise” landscaping principles. These principles recognize cool-season turfgrass as an appropriate use of water in high visibility, multi-functional, high-use areas, and parkways typically fit that description.

Cool-season turfgrass can be reasonably drought tolerant, depending on the species and improved variety.

Problems resulting from periods of neglect are relatively easy to correct, and the turf rarely, if ever, needs replacement.

Non-gardeners and typical commercial crews can readily maintain cool-season turfgrass. It naturally inhibits weeds, and mowing is an efficient way to control weeds that do occur. It works well in conjunction with street trees with tolerance for shading. In winter, dormant turf is easy to keep tidy and trash-free. It tolerates foot traffic better than any other living ground cover.

Turfgrass parkways provide continuity and multiple functions.

Blue Grama and Buffalograss have very low irrigation and mowing needs. They are active and green for a shorter season than cool-season turfgrasses, but have an attractive straw color when dormant. They can offer a beautiful alternative to cool-season turfgrasses with their fine textures and soft gray-green color. They require full sun and significant weed control to maintain a high quality appearance in city landscapes. They do not tolerate shady spots, high levels of foot traffic, or overwatering. They are not as competitive with weeds, and weeds stand out in contrast to the texture and color of the grasses.

4.2.1 Requirements.

Section 5 includes parkway landscaping standards for Arterial Streets. Section 6 includes parkway landscaping standards for Collector and Local Streets.

4.3

PARKWAY LANDSCAPING -

ALTERNATIVES TO TURF-TYPE

GRASS

Mulched planting beds can be an acceptable alternative solution to turfgrass for parkway landscaping in some situations.

This alternative typically requires less water than cool-season turfgrass. With appropriate plant selection and proper maintenance it can offer seasonal interest and add character. While maintenance needs can be less frequent than a cool-season turfgrass mowing regime, they can be more complex and occasionally more time-consuming as weeding, trimming, mulching and replacing materials are important to keep the plantings healthy and attractive.

Mulched planting bed in the parkway limits water use and can provide visual interest.

4.3.1 Where Appropriate.

Alternatives to irrigated turfgrass can be an appropriate choice for property owners abutting collector and local streets, depending on whether the parkway is governed by an approved Development Plan. Alternatives can also be appropriate for arterial street projects in special plan areas that have recommended alternatives.

4.3.2 Requirements.

Section 5 includes parkway landscaping requirements for Arterial Streets.

Section 6 includes parkway landscaping requirements for Collector and Local Streets.

4.4

SIGHT DISTANCE TRIANGLES AT

INTERSECTIONS

Sight distance generally refers to the line of sight from a driver at an unsignalized intersection to approaching vehicles that the driver needs to see in order to safely enter traffic.

4.4.1 Requirements.

A visual sight distance triangle, free of any structures or landscape elements shall be maintained at street intersections and driveways, as required in Figure 7-16 in the Larimer County Urban Area Street Standards.

Deciduous trees may be permitted to encroach into the clearance triangle provided that the lowest leaves shall be at least six (6) feet from grade and are spaced so that they do not obstruct line of sight.

Site Distance Triangle concept.

Distance 1

D is ta n c e

D e p e n d s o n S p e e d

4.5

LOW IMPACT DEVELOPMENT –

STORMWATER MANAGEMENT

In a “Low Impact Development” (LID) approach to streetscapes, landscaped parkways and medians are depressed rather than raised, to help manage stormwater runoff closer to the source.

Depressed landscape areas are designed with special soil mixes, corresponding plantings, and other design techniques to infiltrate and filter runoff, instead of concentrating and conveying all runoff to centralized detention and treatment facilities.

The City’s Stormwater Criteria Manual, which governs the management of stormwater in the city, describes design, plant selection, and maintenance techniques applicable to streetscapes.

4.5.1 LID encouraged.

LID techniques and technologies are encouraged whenever the drainage patterns and the infrastructure allows for such measures to be used.

4.5.2 Low Impact Development

streetscape projects.

In any streetscape where a Low Impact Development approach is used, Streetscape Standards shall be adapted or modified as needed per the Stormwater Criteria Manual.

Illustration of LID concepts in a parkway.

Illustration of LID concepts in a parkway.

Illustration of LID median concept with street runoff directed to a depressed median with a flush band instead of curb and gutter.

Illustration of LID median concept with street runoff directed to a depressed median with special curb and gutter inlets.

SECTION 5

Arterial Streets The city’s arterial streets are complex and expensive public infrastructure, combining virtually all utility and transportation systems of the city.

Besides the functional needs for traffic and utilities, a pervasive theme throughout the City’s Comprehensive Plan is the importance of streets as public space. As high-visibility public space, arterials create first impressions, are experienced by all residents on a daily basis, and play a large role in determining the character and conveying the civic intention of the City.

Arterial streetscapes vary widely, from the Downtown core, to suburban residential areas, to the Natural Areas in the Poudre River valley.

Downtown core.

Suburban residential area.

Poudre River valley.

Some arterials are distinguished by the inclusion of medians along street corridors and in roundabouts. Besides managing traffic, medians provide very high-visibility space for landscaping, and provide a refuge for pedestrians crossing the road.

Medians can humanize the scale of a wide street, and add beauty and civic identity.

They are a highly visible mainstay of urban design, and thus are a major aspect of the City’s streetscape efforts.

Medians in a roundabout.

5.1

ARTERIAL STREETSCAPES MAP

The Arterial Streetscapes Map recognizes differences between various arterials throughout the city. It indicates where a “Standard Arterial Streetscape” approach should apply, and where other corridor segments and gateway intersections warrant their own tailored approach to streetscape design and management.

The map works in conjunction with design standards in the following chapters to guide investment in streetscapes throughout the city.

The types of Arterial Streetscapes and Gateways are:

• Standard Arterial Streetscapes.

• Enhanced Travel Corridors.

• Special Planning Areas.

• Streetscapes constrained by

Existing Development.

• Gateway Intersections.

• Community Entrance Gateways

• (at Interstate 25).

5.2

ARTERIAL STREETSCAPE DESIGN:

STANDARD ARTERIAL

STREETSCAPES - MEDIANS

The primary focus of “Standard Arterial Streetscapes” is on medians, including the medians in roundabouts.

Median standards emphasize mixed plantings of perennials, grasses, shrubs, and tree groupings, with a mulched ground surface. The intent of these standards is to reflect a City’s western regional character with regionally-specific plants suited to the harsh roadway environment.

Planting compositions must include:

• Varied plant forms, textures, and foliage in addition to flowers.

• Coordinated, repeating groupings of plants to form an overall pattern.

• Accent groupings to add detail and variation within the overall pattern.

• Related elements such as mulches and boulders.

Illustration of standard arterial median landscaping approach.

5.2.1 Median width measurements.

All references to median widths are from face of curb to face of curb.

5.2.2 Median grading.

The ground surface in landscaped medians shall be crowned with a high point in the center, with slopes not to exceed 7:1 or approximately 14 percent. This standard shall not apply where a median has a cross slope due to opposing traffic lanes and curbs having different elevations, such that a crown may not be feasible.

5.2.3 Median grading in

roundabouts.

The ground surface in center medians in roundabouts shall be crowned with slopes not to exceed 7:1 or approximately 14 percent. The intent of this standard is to increase the visual prominence of landscaping, and work in conjunction with planting and hardscape elements to achieve year-round screening of visibility across the roundabout to a height of at least 4 feet.

5.2.4 Median planting general

approach.

Tree groupings and mixed plantings of other plant types shall be established and maintained in medians.

This standard shall not apply in the following situations:

• Trees shall not be planted in medians less than seven feet wide.

• Medians less than three feet wide shall be paved rather than planted.

5.2.5 Median tree groupings:

• Canopy shade trees, ornamental trees, and evergreen trees shall be planted in groups of three, five, or more to the extent reasonably feasible. Open intervals shall be provided between the groups.

• Open intervals between tree groups shall constitute 30-60% of the length of a given median. These percentages are intended to convey a general proportion rather than a precisely measured formula.

• Determination of the open intervals shall be based on the design intent and growth assumptions for trees over a given time frame.

• Where median length allows, repetition of tree groupings is encouraged.

5.2.6 Tree separation from median

edges.

Separation of trees from concrete edges shall be provided by designers as needed based on assumptions for growth and pruning over a given time frame. The following minimum separations shall be provided for tree types as listed in Exhibit List of Recommended Plants:

Large canopy trees – 2.5 feet.

Ornamental trees – 1.5 feet.

Large evergreen trees – 7 feet.

Small evergreen trees – 5 feet.

5.2.7 Evergreen tree

setbacks from face of curbs.

Evergreen trees shall be set back from the face of curbs:

Large evergreen trees – 9

Small evergreen trees – 7

5.2.8 Staggered median

tree groupings if space permits.

Tree groupings shall be staggered rather than aligned in straight rows, where median width permits a stagger of at least 2 feet.

Example plan view of a median showing tree groupings.

5.2.9 Mixed plantings.

Mixed plantings of perennials, ornamental grasses, shrubs, and shrubby trees shall be planted and maintained to cover at least 75% of the median area within 5 years, based on assumptions for growth and maintenance of plants by the designer.

• Mixed plantings shall be composed of groups of at least 3 plants per group, with each group composed of a single species.

• Mixed plantings shall be composed for understory conditions at tree groupings, and open conditions in intervals between tree groupings.

Mixed planting in a newly planted median.

• Mixed plantings shall be arranged in an informal pattern rather than formal rows or geometrically-shaped groupings. The informal pattern shall include coordinated, repeating groupings of plants in an overall composition, rather than random placement. Plantings shall be designed and maintained to span the full width of the median at maturity.

• Mixed planting standards apply to all medians 3 feet wide or wider.

This – informal pattern, but with repeated groupings to create an overall order in the design pattern.

Not This – formal, geometric pattern of massed plantings. While this kind of design pattern is not the “Standard Arterial Streetscape” approach, it may be appropriate for special planning areas.

5.2.10 Mixed plantings – two options

for intensity.

Two options for mixed plantings shall be permitted:

• Perennial Garden Style.

• Shrub Garden Style.

Perennial Garden Style: This option emphasizes the maximum degree of planting intensity, color, and variety, with perennials used for the full length of a median. This results in a higher number of different plant groupings and a higher total number of plants to achieve the required 75% plant coverage.

Shrub Garden Style: This option allows the use of larger shrubs and shrubby trees to achieve the required 75% coverage with a lower number of different plant groupings and lower total number of plants.

5.2.11 Perennial Garden Style

requirements.

An average of at least 4 groupings of perennial or ornamental grasses, and 3 groupings of shrubs per 250 square feet shall be planted and maintained.

Groupings shall be composed of single species with at least 3 plants.

Illustration of Perennial Variety Style mixed planting, with open areas and tree groupings.

5.2.12 Shrub Garden Style

requirements.

An average of at least 3 groupings of shrubs per 250 square feet shall be planted and maintained. Groupings shall be composed of single species with at least 3 plants.

In open areas at the ends of medians at intersections, at least 4 perennial or ornamental grass groupings and 3 shrub groupings shall be planted and maintained, with emphasis on color and/or texture over a long growing season.

Example of a mixed shrub planting with regionally adapted species (not a streetscape).

Plan view illustrations comparing perennial variety concept (on the left) and shrub variety concept (on the right) .

5.2.13 Decision on options.

The option to be used in any project shall be approved by the Director based on consideration of the relative importance of a given median to community image, intensity of adjacent land uses, the width and length of the median, and City budget considerations. In general, the Perennial Garden Style is more appropriate in higher-activity, mixed-use areas. The Shrub Garden Style is generally more appropriate in residential and other lower-activity areas.

5.2.14 Median noses and narrow

ribbons - planting.

Median areas 3-7 feet wide shall be planted with low mixed planting under 30 inches in height.

5.2.15 Plants and mulches in

conjunction.

Plant groupings shall be designed in association with either cobble mulch or organic mulch. Plants selected to feature green leaves and flowers are generally complemented by organic mulch, while stone mulch can detract from their effects. Stone mulch can complement evergreens, other plants selected to feature distinct forms or textures, and xeric plants with grey-green foliage.

When mulches are mixed, the patterns shall be in sweeping curves, and not rectangular blocks or strips along the edge.

5.2.16 Mulches.

Organic mulch shall be used, either solely or in combination with stone mulch to add visual interest with a design pattern. Organic mulch shall be undyed shredded woody material. If a combination is used, the pattern shall be designed in conjunction with plant groupings, and the pattern shall span the full width of the median rather than dividing the median lengthwise into linear strips or lining the edge of the median.

This - mulch pattern spans the median in a sweeping curve.

Not this – mulch pattern in linear strips.

This – mulch pattern in sweeping curves designed with the direction of travel in mind.

Not this – mulch pattern in linear strips.

Not this – mulch pattern in blocks.

Stone mulch, if used, shall consist of 2- 4-inch stone combined with groupings of 4-12 inch or larger stone hand placed as accents for visual interest and to separate abutting organic and stone mulches. Larger stone shall be placed first, to be embedded, mingled, and settled with the smaller stone rather than loosely dumped.

Stone mulch placement example.

5.2.17 Boulders.

Boulders may be used to structure and complement plant groupings. They shall be designed and placed in deliberate groupings in association with the planting and mulch design pattern, and any low walls or slopes. They shall be placed prior to planting and mulching, and slightly sunk into the ground, to be embedded and mingled with mulches and plantings. Permitted boulders shall be tan Masonville sandstone quarry blocks, rounded river boulders, or weathered moss rock boulders.

Boulder selection shall be based on continuing an established theme, or establishing a theme where none exists.

Tan Masonville sandstone quarry blocks.

Rounded river boulders as part of a whole design approach to plantings and mulches.

5.2.18 Median hardscape – edges

and paving.

Hardscape treatments depend on different median widths and different contexts throughout the city, and shall comply with the following requirements:

A. In median areas that are at least 7 feet wide, a double curb edge shall be installed where a project includes 1) a new median, or 2) an existing median that lacks splash blocks or has splash blocks that warrant replacement. The purpose of this standard is to provide additional depth for planting areas, space for maintenance personnel, an additional correction barrier for vehicles leaving the roadway, and a visual design that complements the curb and gutter. Where a median tapers to less than 7 feet, the upper curb shall return across the median to enclose the upper landscape area.

6”

Illustration of double curb.

The following exceptions to the double curb shall apply:

1) Sloped concrete splash blocks with integral tan tint and exposed aggregate finish shall be permitted in lieu of a double curb if a median project is located in a street segment or area of the city where existing splash blocks have a previously established theme and are expected to remain for a long

Standard curb and gutter

Double curb design.

12”

Tan-tinted concrete term.

Sloped splash block design.

18” 6”

8”

Sloped splash block design: existing Standard Arterial Streetscape corridors throughout the city include extensive segments with existing sloped concrete splash blocks, per a former standard.

2) Where a median is less than 7 feet wide, the edge shall be a standard 6-inch curb with no double curb or splash block.

B. Median areas under 3 feet wide shall be paved rather than planted.

Paving shall be rectangular concrete or brick pavers set on a concrete base.

The following exception to pavers shall apply: where existing tan exposed-aggregate concrete median paving establishes a prevailing theme, it shall be permitted for paving of medians under 3 feet wide.

Tan exposed-aggregate concrete median paving.

Rectangular pavers set in a herringbone pattern.

Median area 7 feet or wider – mixed planting and ornamental trees to provide a sense of pedestrian scale. Double curb continues to crosswalk.

Narrow median area 3-7 feet wide – mixed planting, no trees, standard curb.

Narrow median area under 3 feet wide – pavers, standard curb.

5.2.19 Roundabout

planting and hardscape:

Roundabout medians in Standard Arterial Streetscape areas shall be developed and maintained with tree groupings and mixed plantings in the Perennial Variety Style, with boulders and a mulched ground surface. Landscape walls may be included to reinforce the pattern and provide year-round structure for plantings.

Apron paving and any special curbs shall be designed for visual interest with tinted, textured concrete, pavers, or similar material.

Design of each individual roundabout shall be unique unless multiple roundabouts are related in a pair or group as part of a single traffic management project.

Design elements include planting themes, plant species, apron paving, and other hardscape details.

Mixed planting, trees, mulches, boulders, and landscape walls in a coordinated pattern

Specialty apron paving in a coordinated pattern

Plan view of roundabout components.

Illustrations of roundabout landscaping approach with mixed planting, boulders, mulch and hardscape patterns all designed in conjunction. Lower graphic shows the inclusion of landscape walls.

5.3

STANDARD ARTERIAL

STREETSCAPES - PARKWAYS

The City maintains most arterial street parkways, with exceptions in a limited number of situations where other arrangements are made with another entity. Turfgrass provides a range of benefits as a solution to arterial street parkways as described in Section 4.

The benefits describe are relevant for all street classifications, but are particularly relevant for arterials which form a continuous city-wide framework of public space.

5.3.1 Irrigated Turfgrass.

Parkways in Standard Arterial Streetscapes shall consist of irrigated turfgrass and street tree plantings as described in Chapter 4. Appropriate irrigation shall be provided to maintain health of plantings with efficient use of water.

Arterial street parkway.

5.4

ARTERIAL STREETSCAPE DESIGN:

ENHANCED TRAVEL CORRIDORS

(ETC’S)

Standard Arterial Streetscape standards may or may not be adequate and appropriate for design and maintenance of these corridors, depending on unique circumstances in each ETC.

These arterial corridors are intended to evolve as a framework that incorporates and supports high frequency transit with special emphasis on walkability and bicycling.

5.4.1 Tailored streetscape approach.

For streetscape projects where previous ETC plans do not define a streetscape approach, the Standard Arterial Streetscape standards in Section 5.2 shall be considered as the minimum requirement for the level of quality and investment.

Design and maintenance shall then be adapted to unique circumstances in each corridor as appropriate, based on study of and response to:

1. Guiding policies for ETC’s.

2. Established precedents in the corridor that are consistent with the vision and policies for ETC’s.

Examples of permissible design variations include:

3. Planting patterns to reinforce the pattern of transit facilities.

4. Hardscape elements – edge treatments, paving, planters, and the like, particularly where related to transit stops and shelters.

5. Urban design amenities in a coordinated program, particularly including paving, furnishings, and structures at transit stops and shelters.

In all cases, design shall include repeating elements to create a theme for the corridor and avoid clutter of unrelated elements.

5.5

OTHER SPECIAL PLANNING

AREAS

Special planning areas have subarea plans, corridor plans, or other planning documents that recognize their unique context and character. The level of specific direction for streetscapes varies among the plans.

These areas warrant their own distinctive streetscapes with tailored design and maintenance characteristics, rather than the Standard Arterial Streetcape.

5.5.1 Tailored streetscape approach.

For streetscape projects where plan documents are not definitive, the Standard Arterial Streetscape standards in Section 5.2 shall be considered as the minimum requirement for the level of quality and investment, and may be considered as a reference for design.

Design and maintenance shall then be adapted by project designers and staff based on study of and response to the context and any established precedents that are consistent with the vision and policies for the area, and are thus expected to remain.

Examples of permissible design variations on the Standard Arterial Streetscape include:

6. Distinct patterns of trees and other plant groupings.

7. Signature plant species.

8. Hardscape elements – edge treatments, paving, low planter walls or landscape walls, and the like.

9. Urban design amenities such as paving, street furnishings, and transit stop shelters or other themed structures in a coordinated program.

In all cases, design shall include repeating elements to create a theme for the area and avoid clutter.

Custom-tailored streetscape with parkway and median details as part of a whole planning approach to a street segment in Campus West.

5.6

CONSTRAINED CORRIDORS AND

SEGMENTS

These are arterial corridors and segments where the Standard Arterial Streetscape is not feasible due to physical constraints of existing development. Typically, both parkways and medians are constrained.

Example of a constrained arterial (East Prospect).

5.6.1 Tailored streetscape approach.

Streetscape projects in these areas shall incorporate aspects of a Standard Arterial Streetscape to the extent reasonably feasible. The allocation of available space and the compromises on each component of the street shall be determined on a project-by-project basis.

The most important aspects to consider in the streetscape approach are safe sidewalks and street trees as described in Chapter 4.

5.7

GATEWAY INTERSECTIONS

These intersections are exceptional locations where the Standard Arterial Streetscape should be augmented with additional intensity of streetscape development in any capital projects.

These locations warrant the highest level of investment for design, construction and maintenance.

The intent is to highlight entryways into the city, and also edges of districts within the city. The locations consist of intersections, whether signalized or roundabouts, extending outward as appropriate to include medians associated with the intersection.

5.7.2 Components.

Streetscape projects at gateway intersections shall be enhanced with a coordinated program of components including at least four of the following:

• Plantings of annual flowers in beds or large pots.

• Railings or low walls.

• Bollards.

• Pedestrian lighting/ other specialty lighting.

• Columns, pylons or other urban design structures.

• Signal or light pole treatments.

• Color themes in repeated components.

• Special paving.

• Sculpture or other public art in addition to the components listed above.

Examples of enhanced gateway components – annual flowers, planter pots on plinths, railings, pedestrian lights, public art pylons, and tinted concrete paving.

Example of a median approaching a gateway intersection incorporating themed railings mingled with plant groupings.

Illustrations of themed plantings, walls, median planters, and specialty paving as exampes of special treatments to mark an enhanced gateway signalized intersection (above) and gateway roundabout (below).

5.8

Example of enhanced gateway components at an I-25 Interchange, including stone walls and a themed planting design.

SECTION 6

Collector and Local Streets 6.1

PARKWAY LANDSCAPING

Streetscapes on collector and local streets typically consist of parkways only. The primary intent for parkway landscaping is to provide a setting for street trees, and work in conjunction with street trees for a number of purposes:

• Define streets as the framework of public space within which individual properties fit.

• Contribute to the attractiveness and visual interest of the street edge.

• Mark the transition from public to private space.

• Blend public interests in street infrastructure with interests of abutting property owners who are required to maintain these parkways by City Code.

6.1.1 Two approaches.

Two main approaches to landscaping parkways are permitted in collector and local streets: turf-type grasses, and mulched planting beds. Pros and cons of each are discussed in Section 4.

In both approaches, appropriate irrigation shall be provided to maintain health of plantings with efficient use of water.

In developments where there is no development plan that specifies parkway landscaping, the owner of the property abutting the parkway may select either approach, regardless of any Homeowner Association covenants that may apply to the development, and shall be responsible for the installation and maintenance of the parkway landscaping in accordance with Section 24-42 of the City Code.

6.1.2 Approved development plans

govern.

In developments with approved landscape plans, the parkway landscaping must be in accordance with the plan.

A Homeowners Association (HOA), or a property owner with notice to and opportunity for comment from the HOA, may request a Parkway Landscaping Amendment to an approved plan for parkway landscaping.

Such a request by a property owner shall be limited to the parkway strip abutting the lot of the property owner and shall be reviewed by the Director in accordance with Section 2.2.10(D) of the Land Use Code.

6.1.3 New development landscape

plans.

Where a developer desires to offer non-turf grass options to homeowners, the landscape plan shall contain notes and drawings specifying options for non-turf ground cover plantings, with consistent mulch and a recommended plant palette.

6.1.4 Turf-type grass.

Turf-type grass shall be permitted, including both cool-season turfgrasses and warm-season native shortgrasses as discussed in Section 4. The choice of grass species and variety can make a major difference in water use needs, ease of establishment, survival of the grass, weeding, mowing, and renovation requirements.

Cool-season turfgrass parkway congruent among properties along the street, and also congruent with adjoining landscaping.

6.1.5 Mulched planting beds.

Non-turf ground cover plantings shall be permitted, including mulched planting beds and ground cover plantings. With an understanding of plant selection and proper irrigation and maintenance, these plantings can provide seasonal interest with little water required.

Property owners are encouraged to incorporate choices that provide a degree of congruence with neighboring properties in terms of mulches and character of plantings.

Mulched planting bed with a perennial garden in a parkway.

Combination of turf and planting beds in parkway areas.

6.1.6 Requirements for non-turf

ground cover plantings:

A. Landscaping shall be designed, installed and maintained so that at least 50% of the area shall be covered with live plant material within 3 years from installation.

B. Plant materials shall be under 2 feet tall if within 5 feet of a driveway and under 3 feet tall in other areas.

Owners are encouraged to select plants that maintain these height limits with little or no pruning.

C. Plant materials must not obscure the line of sight for traffic or obstruct the sidewalk. Plantings of any height that obstruct the line of sight or cause safety concerns may be required to be kept trimmed to a lower height or removed so visibility is provided/maintained.

D. No fences or thorny/prickly plant material are allowed.

E. In mulched planting beds, the soil surface shall be 2-3 inches below the curb and sidewalk to allow for mulch to be contained. To avoid clutter, no additional timbers, concrete products, plastic or metal

This – organic mulch, healthy plants, and stepping stones if needed.

edging, or similar material shall be included.

F. Exception: if edging is needed to keep turfgrass out of mulched areas, perpendicular to the street, such edging shall be flush or within 1 inch of the ground surface, so it is not a visible element.

G. Plant materials and mulch must be kept off the street and sidewalk.

H. Avoid cutting tree roots if converting an established turf parkway to a planting bed. Within a tree’s dripline, minimize grade change to protect the tree roots.

Not this – gravel that is not congruent with any other portions of the streetscape, dead plants, weeds, concrete products, and exposed fabric prevent this parkway from contributing to the street as attractive public space.

SECTION 7

Maintenance Standards The purpose of this Section is to foster a consistent, high quality appearance for all streetscapes, whether maintained by the City, its agents, or by private developers, businesses, or individuals.

Given the high visibility of city streetscapes, the public is able to observe maintenance practices in the field as well as the results of that maintenance. The public perception of a well-maintained landscape is promoted by practices which benefit the health of the landscape materials and achieve a neat, well-cared for appearance. Quality maintenance is a function of workmanship, funding, knowledge, and technique. These standards attempt to ensure that all streetscapes are cared for in a manner which reflects the high esteem that citizens have for these important public spaces. Generally, all landscaping shall be maintained in a healthy condition throughout the growing season. A neat and attractive appearance is essential.

Irrigation systems, structures, and sidewalks shall be maintained to represent the original integrity of the design and installation.

7.2

MAINTENANCE

RESPONSIBILITIES

Maintenance responsibilities vary among different street types, and also with specific circumstances of abutting properties.

7.2.1 Maintenance responsibilities

standards and requirements:

A. Street trees located on the City right-of-way are the responsibility of the City Forestry Division to manage, maintain, and replace on all streets, regardless of who maintains the surface.

B. Exception: some streetscape projects include a warranty period for establishment of newly planted trees in which the project is responsible.

C. Medians in arterial streets shall be maintained by the City.

Exception: some streetscape projects include a warranty period for establishment of median landscaping in which the project is responsible.

D. Parkway landscaping on Collector and Local streets shall be maintained by the adjacent property owner in accordance with City Code.

E. Parkway landscaping on arterial streets shall be the responsibility of the City if there is no individual, organization, or homeowners’ association that prefers to maintain them, or that can be fairly allocated the maintenance responsibility based on their unique benefit .

F. The following four other different scenarios for planting and continuing maintenance are possible depending on circumstances:

1) The developer installs the landscape and the City takes responsibility for tree maintenance after a warranty period for full tree establishment during which time specific obligations are met. The surface (turfgrass, other plantings, mulches, irrigation) must continue to be maintained by the developer, homeowners’ association, or other responsible party.

2) The developer installs the landscape and after meeting obligations during the first two years, the City takes responsibility for both tree and surface maintenance.

3) The landscape is part of a Capital

Improvements Project and a contractor does the landscape work.

The City is responsible for tree maintenance and may or may not be responsible for surface maintenance.

4) Adopt A Median -- the City encourages homeowners’ associations, business groups, and other civic groups to take part in the Adopt-A-Median program.

Contact the City Parks Division at 221-6660 for further information.

7.3

ACCEPTANCE OF NEW ARTERIAL

STREETSCAPE PROJECTS FOR

CITY MAINTENANCE

7.3.1 Streetscape installed to City

standards.

Any new streetscape landscaping not designed and installed to these standards may be rejected by the City Parks Division for inclusion in its maintenance program. Developers and City capital projects shall notify the City Parks Division and conduct a walk-through with Parks and Forestry Division staff at the end of the warranty period.

Any defects in the landscaping or irrigation system shall be corrected by the project that installed the streetscape.

7.4

GENERAL MAINTENANCE

STANDARDS

7.4.1 Trash.

Trash shall be removed on a regular basis.

7.4.2 Turf-type grass.

Cool-season turfgrasses shall be maintained at a 3-inch cut during the growing season. Trimming shall be concurrent with mowing, to match height of open turf, around mowing obstructions such as trees, curbs, and vacuum breakers. Turfgrass shall be edged concurrent with mowing when needed to prevent growth over edges.

Visible clippings shall be removed from sidewalks and streets.

Buffalograss and Blue grama shall be maintained at a maximum height of 12 inches.

7.4.3 Shrubs.

Shrubs shall be pruned as needed to: 1) achieve the design intent; 2) remove dead or diseased branches; and 3) support plant health and vigor. Dead shrubs shall be removed and replaced immediately. Shrubs shall not extend over the curb or sidewalk.

7.4.4 Perennials.

Perennials shall be deadheaded and trimmed throughout the growing season as appropriate for the design intent for each species. Depending upon design intent, perennials and ornamental grasses shall be cut back in late fall or early spring prior to new growth. Dead perennials shall be removed immediately and replaced per the design intent.

7.4.5 Annuals.

Planting of annuals in the spring shall be in designated annual flower beds.

Annuals shall be regularly deadheaded of spent blooms. Annuals shall be removed in the fall after the first hard freeze.

7.4.6 Mulch.

Mulch shall be replenished as needed to maintain complete coverage of the soil surface with a depth of 2-4 inches, with careful placement and reduced depth as needed underneath plants to avoid burying leaves or tender stems.

7.4.7 Weeds.

All landscaped areas shall be kept free of weeds and invasive grasses that are not part of the design intent. Weeding may be done manually or by the use of herbicide and or pre-emergent. The use of any restricted herbicides or soil sterilants is prohibited. In accordance with Best Management Practices, the effectiveness of the herbicide shall be monitored.

SECTION 8

Irrigation Standards Proper watering systems help achieve City goals and citizen expectations for public spaces. Irrigation of parkway and median plant material is necessary to maintain a quality appearance and long term health of streetscape plantings.

It is the City’s intent to be a good steward of water resources consistent with “xeriscape” and “water-wise” principles related to social, environmental, and economic sustainability.

All irrigation systems will be designed to meet the needs of each unique landscape by following best management practices and up-to-date technology. Without proper irrigation design and maintenance, good stewardship of the landscapes is not achievable.

8.1

IRRIGATION SYSTEM DESIGN

8.1.1 General design standards.

Irrigation design and installation shall comply with the following general standards:

A. Irrigation design shall be done by a certified irrigation designer unless otherwise approved by the Parks Department.

B. Irrigation system design and installation shall be monitored, inspected, and approved by the City Parks Division. Irrigation systems shall be installed and maintained so that irrigation equipment will not spray onto any streets, walkways, or features and structures that could be damaged by water.

C. The irrigation system must comply with the International Plumbing Code and with the City Electrical Code.

D. Any deviation in taps from the approved construction plans must be approved by City Utilities prior to installation. Any water service line shall be coordinated with City Utilities.

E. Any deviation in layout of the irrigation system from the approved construction plans must be reviewed and approved by the City Parks Division prior to or during installation.

F. The irrigation system shall be designed to provide full coverage and matched precipitation rates.

G. Lateral piping shall be sized based on flow demands in gallons per minute (gpm); with velocities not to exceed 5.5 feet per second.

H. Xeriscape principles shall be utilized in the design of the irrigation system.

I. All designs shall meet the industry’s Best Management Practices from the Irrigation Association and ALCC (Associate Landscape Contractors of Colorado).

J. Newly installed irrigation systems shall be subject to water audits.

K. The minimum distribution uniformity for spray heads shall be .55; for rotor heads it shall be .65;

for stream rotors it shall be .75;

and for impact heads it shall be .65.

L. Design considerations shall include:

1) shrub and perennial beds are to be zoned separately from turf areas; 2) sloped areas will have separate zoning for heads at the higher elevations from those at the lower elevation; 3) areas with different exposures are to be zoned separately; and 4) In-head check valves are to be used for all areas adjacent to walkways and at the bottom of berms and pond areas.

M. Xeric irrigation and drip systems come in a wide variety of configurations. The correct application shall be approved for each landscape design by the City Parks Department.

N. Trees planted in non-turf irrigated landscape areas require short-term and long-term irrigation and should be on individual or separate zones.

Supplemental emitters shall be installed on top and around the root ball for short term health.

Perimeter irrigation of the root ball shall be installed for long term and permanent irrigation.

O. The contractor shall install the saddle for the PVC or AC pipe.

P. The backflow prevention device and water meter shall meet the City standards, and the flow meter shall be Data Industrial.

Q. A curb stop shall be installed between the meter pit and the backflow prevention device for isolation purposes. The curb stop shall be sleeved from the valve to grade and covered with a round valve box.

R. A blowout tube no larger than ¼” shall be placed between the meter pit-curb stop and the back flow prevention device. The injection port on the blow out tube shall be sweated on, attaching a female adapter with a threaded brass plug.

S. A blowout tee shall be installed immediately downstream of the backflow prevention device.

8.2

MATERIALS STANDARDS

8.2.1 Pipe:

A. Copper shall be type K rigid conforming to ASTM Standard B88.

B. Mainline shall be Class 200 PVC, NSF approved. If 3 inches or larger, use ringtite pipe.

C. Laterals shall be Class 200 PVC, NSF approved.

D. No laterals shall be smaller than 1-inch pipe.

E. Trickle tubing shall be weather and

UV resistant material.

F. Polyethylene drip pipe shall be NSF approved, SDR pressure-rated pipe, only as approved for drip applications.

G. Funny pipe shall be used only for pop-up spray heads, and shall be compatible with the elbows needed for the sprinkler heads.

H. Lateral fittings shall be Schedule

40, Type 1, PVC solvent-weld, with ASTM Standards D2466 and D1784.

I. Copper or cast bronze fittings, soldered or threaded per installation details shall be used for all copper pipe.

J. Mainline fittings shall be ductile iron for 3-inch and larger pipe; and shall be PVC Schedule 80 for smaller pipe.

K. Sleeving shall be ductile iron or

PVC pipe under all paved surfaces.

Sizes shall be a minimum of two sizes larger than the pipe being sleeved, but shall in no case be smaller than 2-inch diameter pipe.

8.2.2 Valves:

A. Remote control zone valves shall be electrically operated, appropriate for the water supply, with manual bleed device and flow control stem. Valves shall have a slow-opening and slow-closing action for protection against surge pressure.

Brand and model shall be Rainbird PE Series Remote Control Valves, scrubber option with self cleaning screen unless City specifies other brand and model.

B. Valves used for two-wire system shall be properly grounded per manufacturers recommendation.

C. Drip valves, bubbler valves, and micro-spray valves shall be accompanied by pressure-reducing devices matched with recommended filters to assure proper operation and reduced failure of such equipment.

D. Isolation gate valves shall be

Kennedy 1571X or Matco #100M, able to withstand a continuous operating pressure of 150 psi.

Clear waterway shall be equal to full diameter of pipe. Shall be opened by turning square nut to the left (wheel opening is unacceptable).

E. Manual drain valves shall be ¾-inch ball valve with tee handle, Watts #B-6000, or approved equal.

F. Quick coupler valves shall be 1-inch brass, Rainbird #5RC units with rubber cover. Supply 1-inch brass key for Rainbird 55K.

G. Spears True Union ball valves shall be installed upstream of the remote control zone valve.

Equivalent substitutes shall be accepted.

H. Valve boxes shall have matching locking cover which shall be Carson, Pentex or approved equal.

Box sizes shall be as specified to house one valve per box.

8.2.3 Control System:

A. Controllers shall have smart controller technology…